Determination of welding process
1. Welding groove, due to high requirements for groove, all grooves are made by mechanical processing, and both sides of groove are required to be 50? Mm It is forbidden to have impurities such as water, oil and rust.
2. Selection of welding materials: The selected welding materials shall have the same strength as the welding materials, and mixed gas shielded welding shall be adopted. The welding wire is GHS-70 high strength welding wire with a diameter of 65438 0.6 mm. ..
3.？ Adopt argon-rich shielded welding, DC reverse connection.
4.？ Preheating before welding: According to the mechanical properties of NM360, the preheating temperature is 120℃~ 150℃, and oxygen-acetylene gas (or NAS gas) is used for local preheating near the welding area. Pay attention to the preheating temperature can not be too high, otherwise it will increase the high temperature residence time, slow down the cooling rate and appear brittle crack.
5. Adopt mixed gas shielded welding and Ar+CO2 mixed gas shielded welding, in which Ar accounts for 70% ~ 80% and CO2 accounts for 20%~30%.
Process parameters of mixed gas shielded welding
Protective gas: Ar? 80%? Carbon dioxide? 20%
Welding wire diameter: Ф1.6mm.
Welding current: 280~300/A
Welding voltage: 20~30 volts
Welding polarity: DC reverse connection
Welding speed: 0.6 cm/s
Extension length of welding wire: welding wire diameter × 10 ~ 15.
Control of welding stress and deformation
1.？ After welding, you can hammer around the weld to eliminate and disperse the stress.
2.？ Post-weld heat treatment In order to effectively eliminate internal stress, improve the stability of components and improve the mechanical properties of components, post-weld heat treatment can be carried out by tempering at a high temperature of 550℃ according to the actual situation.
3.？ When repairing welding defects, the welding defects should be completely removed, which can be polished by machining or angular grinding wheel. The groove should be suitable, and the range of preheating, layer temperature and post-heating during repair welding should be appropriately relaxed, and the temperature should be consistent with welding.
4.？ Process measures should be strictly formulated and strict inspection should be carried out at the same time to ensure welding quality.
Through the understanding of wear-resistant steel technology, we can better master its production technology and facilitate the development of new wear-resistant steel products. Different types of wear-resistant steel are suitable for different industrial products, but in modern industry, wear-resistant steel with low alloy element content, low price, high hardness, good technological performance and energy saving is most welcomed by industrial producers, thus making it possible to develop low-alloy high-strength weldable steel, and China iron and steel enterprises can keep pace with the world.
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